In the related art, as a vehicle door lock device, a device disclosed in JP 2009-155938A (FIG. 6) (Reference 1) is known. The device is configured to include a latch (latch mechanism) that can hold a vehicle door in a complete-closing state, and a sector gear (actuating lever) that is mechanically linked to the latch and is driven to rotate by an electric motor. The sector gear is actuated to rotate in one direction from a predetermined neutral region toward a closing region in a preset rotation regulating range, and thereby the latch is actuated to hold, in the complete-closing state, the door having been in a half-closed state. Otherwise, the sector gear is actuated to rotate in another direction (reverse direction) from the neutral region to a release region, and thereby the latch is actuated to release the holding of the door in the complete-closing state. After the sector gear is actuated to rotate from the neutral region toward any region, the sector gear rotates to return to the neutral region.
In addition, the device includes a rotary type of first neutrality detecting switch and second neutrality detecting switch. FIG. 9 is a view illustrating a simplified relationship between a rotating position of a sector gear within a rotation regulating range and logic (H or L level) of a detection signal that is output from the first neutrality detecting switch and the second neutrality detecting switch, corresponding to the rotating position. In the same figure, the first neutrality detecting switch generates a first neutrality detection signal having logic that is switched at a first neutral position which is a boundary position between the neutral region and the closing region, and the second neutrality detecting switch generates a second neutrality detection signal having logic that is switched at a second neutral position which is a boundary position between the neutral region and a release region. In other words, the first neutrality detecting switch generates the first neutrality detection signal that has the H level in the closing region, and has the L level in the neutral region and the release region. The second neutrality detecting switch generates the second neutrality detection signal that has the H level in the release region, and has the L level in the neutral region and the closing region. Hence, both of the first and second neutrality detection signals have the L level, and thereby detecting that the sector gear is in the neutral region.
Normally, when the sector gear is actuated to rotate from the closing region to the neutral region, drive (energization) of the electric motor is stopped, based on the switching of the logic of the first neutrality detection signal. At this time, a time lag from the stop of the energization of the electric motor to an actual stop of the rotation of the electric motor occurs, and thereby the sector gear is stopped at a position in the neutral region, which is closer to the release region than the first neutral position. Otherwise, when the sector gear is actuated to rotate from the release region to the neutral region, the drive (energization) of the electric motor is stopped, based on the switching of the logic of the second neutrality detection signal. At this time, the time lag from the stop of the energization of the electric motor to the actual stop of the rotation of the electric motor occurs, and thereby the sector gear is stopped at a position in the neutral region, which is closer to the closing region than the second neutral position.
On the other hand, when the sector gear is actuated to rotate from the closing region to the neutral region, drive (energization) of the electric motor is also stopped, based on the switching of the logic of the second neutrality detection signal, in a case where the logic of the first neutrality detection signal is not switched due to any reason (for example, a mechanical failure). In this manner, even when the logic of the first neutrality detection signal is not switched, the sector gear reaches the second neutral position and thereby the rotation of the sector gear is rapidly stopped (a so-called fail-safe function).
Incidentally, a rotating amount A1 of the sector gear corresponding to the neutral region is set, depending on a rotating amount of the sector gear from the stopping of the energization of the electric motor to the actual stop of the rotation of the electric motor. This is because the sector gear, which returns from the closing region, enters the neutral region even when the time lag described above has an effect on the sector gear. Hence, during actuation of the fail-safe function, even in a case where the energization of the electric motor is stopped, based on the switching of the logic of the second neutrality detecting switch, there is a need to secure a rotating amount A2 equal to the rotating amount A1 and to set a virtual neutral region. With the rotating amount A2 in the virtual neutral region, holding of the door in the complete-closing state needs not to be released even in the release region. In other words, a rotating amount of the sector gear corresponding to the release region, is a total amount (=A2+B) of the rotating amount A2 by which the sector gear is allowed to idle and a rotating amount B obtained when the holding of the door in the complete-closing state is actually released. A rotating amount of the sector gear corresponding to the neutral region and the release region is a total rotating amount (=A1+A2+B) of the regions, and it is inevitable that a rotating amount of the sector gear required to the release of the holding of the door in the complete-closing state increases, that is, that a period of time taken to the release is prolonged.